JP7538790B2 - Exposure apparatus, exposure method, and article manufacturing method - Google Patents

Description

The present invention relates to an exposure apparatus, an exposure method, and a method for manufacturing an article.

In the photolithography process for manufacturing devices such as semiconductor elements, an exposure apparatus is used to transfer an original (reticle or mask) onto a substrate via a projection optical system. Generally, exposure apparatuses that employ the step-and-repeat method (stepper) and exposure apparatuses that employ the step-and-scan method (scanner) are known as such exposure apparatuses.

In an exposure apparatus, in order to accurately transfer the pattern of the original onto the substrate, in addition to aligning the original and the substrate, highly accurate focus alignment is required, and related technologies have been proposed (see Patent Documents 1 and 2). Note that focus alignment refers to the alignment of the image plane of the projection optical system with the surface of the substrate.

Patent Document 1 discloses a technique for improving focus tracking (focus residual) by expressing a processed area (exposure area) on a substrate as a polynomial (approximate surface shape) based on the results of measuring the position of the processed area, and then feed-forward processing the focus correction value. Patent Document 2 discloses a technique for controlling focus using a focus correction value calculated by removing abnormal values from the results of measuring multiple positions on the substrate.

JP 2005-129674 A JP 2016-100590 A

However, if the focus correction value used for focus alignment varies for each exposure area, there is a concern that residuals related to the drive control of the substrate stage (substrate) during focus alignment, i.e., stage control residuals, may be more likely to occur.

The present invention has been made in consideration of the problems with the conventional technology, and has as an exemplary object to provide a technology that is advantageous for suppressing stage control residuals.

In order to achieve the above object, an exposure apparatus according to one aspect of the present invention is an exposure apparatus that exposes a substrate through an original, and includes a substrate stage that holds the substrate, an acquisition unit that acquires the surface positions in the height direction of multiple measurement points of each of multiple exposure regions to be exposed on the substrate, and a control unit that controls the driving of the substrate stage in the height direction when exposing each of the multiple exposure regions based on the surface positions acquired by the acquisition unit, and the control unit determines, for each of the multiple exposure regions, an approximate surface that approximates the cross-sectional shape of the surface of the exposure region from the surface positions acquired by the acquisition unit, and for a first exposure region among the multiple exposure regions in which information about the approximate surface does not exceed a predetermined range, controls the driving based on a correction value for the driving obtained from the approximate surface that approximates the cross-sectional shape of the surface of the exposure region exposed before the first exposure region.

Further objects and other aspects of the present invention will become apparent from the embodiments described below with reference to the accompanying drawings.

The present invention can provide, for example, a technique that is advantageous for suppressing stage control residuals.

1 is a schematic diagram showing a configuration of an exposure apparatus according to one aspect of the present invention. 4 is a diagram showing an example of the relationship between an irradiation system, a light receiving system, and measurement points on a substrate. FIG. 1 is a diagram showing the relationship between measurement points formed in a shot area on a substrate and an exposure area. 11 is a diagram showing measurement points in a shot area on a substrate and measurement results of the surface position at each measurement point. FIG. FIG. 11 is a diagram showing an example of a measurement result of a surface position at each measurement point. FIG. 13 is a diagram illustrating an example of a threshold value set for an approximation surface. 11 is a diagram showing measurement points in a defective shot area on a substrate and measurement results of the surface position at each measurement point. FIG. 11 is a diagram showing the positional relationship of a plurality of measurement points in a defective shot region; 13 is a diagram showing an example of a threshold value set for an approximation surface of a missing shot area; FIG. 13 is a diagram showing an example of a threshold value set for an approximation surface of a missing shot area; FIG. 13A and 13B are diagrams showing an example of an actual cross-sectional shape of a surface of an exposure region, a predicted cross-sectional shape, and threshold values set for an approximation surface of the exposure region; 11 is a flowchart for explaining an exposure process. FIG. 13 is a diagram for explaining an improvement in a stage control residual;

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

Figure 1 is a schematic diagram showing the configuration of an exposure apparatus 80 according to one aspect of the present invention. The exposure apparatus 80 is a lithography apparatus used in a lithography process, which is a manufacturing process for devices such as semiconductor elements, and forms a pattern on a substrate using an original (reticle or mask). The exposure apparatus 80 performs an exposure process in which the substrate is exposed through the original and the pattern of the original is transferred to the substrate.

In this embodiment, the exposure device 80 is a step-and-scan exposure device (scanner) that exposes (scanning-exposes) the substrate while driving the original and the substrate in the scanning direction, thereby transferring the pattern of the original onto the substrate. However, the exposure device 80 can also employ the step-and-repeat method or other exposure methods.

In this specification and the attached drawings, directions are shown in an XYZ coordinate system in which the direction along the optical axis of the projection optical system 14 described below is defined as the Z axis, and two mutually perpendicular directions parallel to a plane perpendicular to the Z axis are defined as the X axis and the Y axis. The directions parallel to the X axis, Y axis, and Z axis in the XYZ coordinate system are defined as the X direction, Y direction, and Z direction, respectively. The rotation direction around the X axis, the Y axis, and the Z axis are defined as the ωX direction, the ωY direction, and the ωZ direction, respectively. In the following description, the Z direction may be referred to as the height direction.

As shown in FIG. 1, the exposure apparatus 80 has an illumination optical system 11, an original stage 13 that holds an original 12, a projection optical system 14, a substrate stage 16 that holds a substrate 15, a first measurement unit 18, a second measurement unit 19, a third measurement unit 17, and a control unit 20.

The control unit 20 is composed of, for example, a computer (information processing device) including a CPU, memory, etc., and controls each part of the exposure device 80 in accordance with a program stored in the storage unit. In this embodiment, the control unit 20 controls the exposure process that transfers the pattern formed on the original 12 to the substrate 15 (scanning and exposing the substrate 15).

The illumination optical system 11 includes a light-shielding member such as a masking blade, and shapes the light emitted from a light source (not shown) such as an excimer laser into, for example, a strip-shaped or arc-shaped slit light having a longitudinal direction in the X direction, and illuminates a part of the original 12 with the slit light.

The original 12 and substrate 15 are held by the original stage 13 and substrate stage 16, respectively, and are positioned at optically conjugate positions via the projection optical system 14.

The projection optical system 14 has a predetermined projection magnification (e.g., 1/2 or 1/4), and projects the pattern formed on the original 12 onto the substrate 15. Hereinafter, the area of the substrate 15 onto which the pattern of the original 12 is projected (i.e., the area irradiated with the slit light, which is the unit of exposure for the shot area) is referred to as the exposure area 21.

The original stage 13 and the substrate stage 16 are configured to be drivable in a direction (e.g., the Y direction) perpendicular to the optical axis of the projection optical system 14 (the optical axis of the slit light). The original stage 13 and the substrate stage 16 are driven (scanned) relatively at a speed ratio according to the projection magnification of the projection optical system 14 while being synchronized with each other. This allows the exposure area 21 on the substrate to be scanned, and the pattern of the original 12 to be transferred to the substrate 15 (shot area). This scanning exposure is repeated sequentially for each of the multiple shot areas on the substrate, thereby completing the exposure process for one substrate 15.

The first measurement unit 18 includes, for example, a laser interferometer, and measures the position of the master stage 13. The laser interferometer included in the first measurement unit 18 measures the displacement of the master stage 13 from a reference position by, for example, irradiating a laser light onto a reflector 13a provided on the master stage 13 and detecting the laser light reflected by the reflector 13a. The first measurement unit 18 can obtain the current position of the master stage 13 based on the displacement of the master stage 13 from the reference position.

The second measurement unit 19 includes, for example, a laser interferometer, and measures the position of the substrate stage 16. The laser interferometer included in the second measurement unit 19 measures the displacement of the substrate stage 16 from a reference position by, for example, irradiating a laser light onto a reflector 16a provided on the substrate stage 16 and detecting the laser light reflected by the reflector 16a. The second measurement unit 19 can obtain the current position of the substrate stage 16 based on the displacement of the substrate stage 16 from the reference position.

The control unit 20 controls the driving of the original stage 13 and the substrate stage 16 in the XY directions based on the current position of the original stage 13 acquired by the first measurement unit 18 and the current position of the substrate stage 16 acquired by the second measurement unit 19. In this embodiment, the first measurement unit 18 and the second measurement unit 19 each use a laser interferometer to measure the position of the original stage 13 and the position of the substrate stage 16, but this is not limited to this and, for example, an encoder may be used.

The third measurement unit 17 is used to align the surface of the substrate 15 (hereinafter referred to as the "substrate surface") with the image plane of the projection optical system 14, and has the function of measuring the position and inclination of the substrate surface. In this embodiment, the third measurement unit 17 measures the surface position (height direction position) of the measurement target portion (measurement point) of the shot area of the substrate 15 held by the substrate stage 16 while the substrate stage 16 is in a driven state. In this way, the third measurement unit 17 functions as an acquisition unit that acquires the surface positions in the height direction of multiple measurement points of the exposure area of the substrate 15 to be exposed.

The third measurement unit 17 is configured, for example, as an oblique incidence type measurement unit that irradiates light obliquely onto the substrate 15. The third measurement unit 17 includes an irradiation system 17a that irradiates light onto the substrate 15, and a light receiving system 17b that receives light reflected by the substrate 15.

The irradiation system 17a includes, for example, a light source 70, a collimator lens 71, a slit member 72, an irradiation optical system 73, and a mirror 74. The light receiving system 17b includes, for example, a mirror 75, a light receiving optical system 76, a correction optical system 77, a photoelectric conversion element 78, and a processing unit 79.

The light source 70 includes a lamp or a light-emitting diode, and emits light of a wavelength to which the resist agent (photosensitive agent) on the substrate is not photosensitive. The collimator lens 71 converts the light emitted from the light source 70 into parallel light with a nearly uniform cross-sectional intensity distribution. The slit member 72 is formed by bonding a pair of prisms (prism-shaped members) together so that their inclined surfaces face each other, and a number of openings (e.g., nine pinholes) are formed on the bonded surfaces using a light-shielding film such as chrome. The irradiation optical system 73 is a double-telecentric system, and each of the light beams that pass through the multiple openings of the slit member 72 is incident (guided) to a number of measurement target locations (measurement points) in the shot area of the substrate 15 via a mirror 74.

The plane (bonding surface) on which the opening is formed and the substrate surface are set so as to satisfy the Scheimpflug condition for the irradiation optical system 73. In this embodiment, the angle of incidence of light incident on the substrate 15 from the irradiation optical system 73 (angle with the optical axis of the projection optical system 14) is 70 degrees or more. As shown in FIG. 2, the irradiation system 17a is configured to cause light to be incident from a direction that forms an angle θ (e.g., 22.5 degrees) with respect to the scanning direction (Y direction) in a direction (XY direction) parallel to the substrate surface. In this way, by causing multiple (e.g., nine) beams of light to be incident on multiple (e.g., nine) measurement target locations on the substrate, i.e., measurement points 30, the surface positions of the substrate surface can be measured independently (individually) at the multiple measurement points 30. FIG. 2 is a diagram showing an example of the relationship between the irradiation system 17a, the light receiving system 17b, and the measurement points 30 on the substrate.

The multiple light beams reflected from each measurement target location (measurement point 30) on the substrate are incident on the light receiving optical system 76 via mirror 75. The light receiving optical system 76 is a double-telecentric system. The light receiving optical system 76 includes an aperture that is provided in common for the multiple light beams reflected from each measurement target location on the substrate, and this aperture blocks high-order diffracted light (noise light) generated due to the pattern formed on the substrate.

The correction optical system 77 includes multiple (e.g., nine) correction lenses, and focuses the multiple lights that have passed through the light receiving optical system 76 on the photoelectric conversion surface (light receiving surface) of the photoelectric conversion element 78 to form multiple pinhole images on the photoelectric conversion surface. For example, a CCD line sensor or a CMOS line sensor is used as the photoelectric conversion element 78. The processing unit 79 calculates (obtains) the surface position of each measurement target location on the substrate, i.e., the substrate surface at the measurement point 30, based on the position of each pinhole image formed on (the photoelectric conversion surface of) the photoelectric conversion element 78. In addition, in the light receiving system 17b, tilt correction is performed so that each measurement point on the substrate and the photoelectric conversion surface of the photoelectric conversion element 78 are conjugate with each other. Therefore, the position of each pinhole image formed on the photoelectric conversion surface of the photoelectric conversion element 78 does not change depending on the local tilt of each measurement point on the substrate.

By configuring the irradiation system 17a and the light receiving system 17b in this way, the third measurement unit 17 can measure the surface position of the substrate surface at each measurement point on the substrate from the position of each pinhole image formed on the photoelectric conversion surface of the photoelectric conversion element 78. Then, in the control unit 20, the drive (focus drive) in the Z direction of the substrate stage 16 is controlled based on the measurement result of the third measurement unit 17 so that the substrate surface of the substrate 15 coincides with the target surface (target height position). Here, the target surface is the image formation surface of the pattern of the original 12, that is, the position of the image surface of the projection optical system 14 (best focus position (optimum exposure position)). However, the target surface does not mean a position that completely coincides with the position of the image surface of the projection optical system 14, but includes the range of the allowable focal depth.

FIG. 3 is a diagram showing the relationship between the nine measurement points 30 (30a ₁ to 30a ₃ , 30b ₁ to 30b ₃ , 30c ₁ to 30c ₃ ) formed by the third measurement unit 17 in the shot area 15a on the substrate and the exposure area 21. The exposure area 21 is a rectangular area shown by a dashed line in FIG. 3. The measurement points 30a ₁ to 30a ₃ are measurement points formed in (the inside of) the exposure area 21. The measurement points 30a ₁ to 30a ₃ are measurement points at which so-called focus measurement is performed, in which the surface position of the substrate surface at the measurement target location on the substrate is measured in parallel with exposure of the measurement target location on the substrate. Moreover, the measurement points 30b ₁ to 30b ₃ and 30c ₁ to 30c ₃ are measurement points formed at positions spaced a distance Lp in the scanning direction (Y direction) from the measurement points 30a ₁ to 30a ₃ formed in the exposure area 21. The measurement points 30b ₁ to 30b ₃ and 30c ₁ to 30c ₃ are measurement points where so-called focus measurement is performed, that is, the surface position of the substrate surface at a measurement target location on the substrate is measured prior to exposure of the measurement target location on the substrate.

The control unit 20 switches the measurement points used for measuring the surface position of the measurement target portion on the substrate, that is, for focus measurement, according to the direction (scanning direction) in which the substrate stage 16 is driven. For example, referring to FIG. 3, when scanning exposure is performed by driving the substrate stage 16 in the direction indicated by the arrow F, focus measurement is performed at the measurement points 30b ₁ to 30b ₃ prior to focus measurement at the measurement points _{30a 1 to} 30a ₃ formed in the exposure region 21. At this time, the control unit 20 determines a command value for locating the surface position of the region including the measurement points 30b ₁ to 30b ₃ at the target height position based on the result of the focus measurement at the measurement points 30b 1 to 30b _3. Then, the control unit 20 controls the focus drive of the substrate stage 16 according to the determined command value so that the region including the measurement points 30b ₁ to 30b ₃ is located at the target height position by the time it becomes the exposure region 21 (reaches the exposure region 21).

On the other hand, when scanning exposure is performed by driving the substrate stage 16 in the direction indicated by the arrow R, focus measurement is performed at the measurement points _30c1 to _30c3 prior to focus measurement at the measurement points _30a1 to _30a3 formed in the exposure area 21. At this time, the control unit 20 determines a command value for locating the surface position of the area including the measurement points _30c1 to _30c3 at the target height position based on the result of the focus measurement at the measurement points _30c1 to _30c3 . Then, the control unit 20 controls the focus drive of the substrate stage 16 in accordance with the determined command value so that the area including the measurement points _30c1 to _30c3 is located at the target height position by the time it becomes the exposure area 21.

Here, a method for improving the synchronization accuracy of the substrate stage 16 when scanning exposure is performed by driving the substrate stage 16 in the direction indicated by the arrow F will be described with reference to FIG. 4. FIG. 4 is a diagram showing measurement points 30c ₁ to 30c ₃ in a shot area 15a on a substrate and measurement results (results of focus measurement) z1 to z3 of the surface position at each measurement point. In the conventional technology, the control unit 20 calculates an approximation surface that approximates the cross-sectional shape of the surface of the exposure area 21 from the measurement results z1 to z3 of the surface position at each of the measurement points 30c ₁ to 30c _3. Then, the control unit 20 controls the focus drive of the substrate stage 16 as described above based on the inclination of the approximation surface (rotation of the substrate stage in the ωX direction and the ωY direction) and the result of the focus measurement. Note that in order to avoid a decrease in synchronization error caused by abrupt driving of the substrate stage 16, the drive amount of the substrate stage 16 is generally provided with an upper limit drive amount (upper limit drive amount). Therefore, in focus drive, if the drive amount of the substrate stage 16 exceeds the upper limit, the substrate stage 16 is driven at the upper limit drive amount.

Below, in each embodiment, a technique for suppressing residuals related to the drive control of the substrate stage 16 during focus drive, i.e., stage control residuals, is described. Note that stage control residuals are one of the causes of focus residuals.

First Embodiment
As shown in Fig. 4, when the cross-sectional shape w1 of the surface of the substrate 15 is a plane, ideally, an approximation surface identical to the cross-sectional shape w1 of the surface of the substrate 15 is calculated, so that the focus drive of the substrate stage 16 is controlled so that the substrate stage 16 becomes a plane. However, in reality, the measurement results z1 to z3 at the measurement points 30c ₁ to 30c ₃ each contain measurement errors s1 to s3 as shown in Fig. 4. Therefore, even if the cross-sectional shape w1 of the surface of the substrate 15 is a plane, the measurement results z1 to z3 at the measurement points 30c ₁ to 30c ₃ each vary as shown in Fig. 5(a) and Fig. 5(b). Fig. 5(a) and Fig. 5(b) are diagrams showing examples of the measurement results z1 to z3 at the measurement points 30c ₁ to 30c ₃ each including measurement errors. Even if the cross-sectional shape w1 of the surface of the substrate 15 is the same planar shape, an approximate surface 100 is calculated from the measurement results z1 to z3 shown in Fig. 5(a), and an approximate surface 101 is calculated from the measurement results z1 to z3 shown in Fig. 5(b). In this way, if the approximate surface calculated from the measurement results at each measurement point varies for each exposure area due to measurement errors, the correction value (focus correction value) related to focus drive obtained from the approximate surface will also vary. As a result, unnecessary disturbance is applied to the drive control of the substrate stage 16, causing a stage control residual (reducing the synchronization accuracy of the substrate stage 16).

Therefore, in this embodiment, a specified threshold range (predetermined range) is set for the approximation surface (the focus correction value obtained from the approximation surface) calculated from the measurement results of the surface position at each measurement point on the substrate. The approximation surface is then compared with the specified threshold range to determine whether or not to apply the focus correction value obtained from the approximation surface to focus driving.

FIG. 6 is a diagram showing an example of a threshold value 102 (range) set for the inclination (rotation in the ωY direction in this embodiment) of the approximation surface 105 calculated from the measurement results at each of the measurement points _{30c 1 to 30c 3.} In this embodiment, the threshold value 102 is set (defined) based on the measurement accuracy 103 of the third measurement unit 17 for the measurement points 30c ₁ to 30c ₃ and the measurement span 104 (measurement range) of the third measurement unit 17 for the measurement points 30c 1 to 30c 3. Specifically, the threshold value 102 (range) is defined by the range sandwiched between two lines 102a and 102b as shown in FIG. 6. The line 102a is a line connecting the lower limit of the measurement accuracy 103 at one measurement point 30c ₁ and the upper limit of the measurement accuracy 103 at the other measurement point 30c ₃ among the measurement points 30c ₁ and 30c ₃ located at both ends of the measurement span 104. Moreover, the line 102b is a line connecting the upper limit value of the measurement accuracy 103 at one measurement point _30c1 and the lower limit value of the measurement accuracy 103 at the other measurement point _{30c3 among the measurement points 30c1 and 30c3 located at} both ends of the measurement span 104. The measurement accuracy 103 may use the standard deviation of the measurement results of the surface position of the third measurement unit 17 at each measurement point evaluated in advance, or may use different values for each measurement point, which is a measurement unit (channel). The measurement span 104 is determined based on the measurement points (effective channels) that can measure the surface position among the multiple measurement points formed by the third measurement unit 17. Therefore, for example, for a missing shot area, the measurement span 104 is determined by excluding the measurement points (invalid channels) that are not on the substrate.

Referring to FIG. 6, in this embodiment, when the control unit 20 calculates an approximate surface 105 whose inclination is within the range of the threshold value 102, the focus drive of the substrate stage 16 is controlled without applying the focus correction value obtained from the approximate surface 105. Specifically, the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the approximate surface that approximates the cross-sectional shape of the surface of the exposure area that was exposed before the exposure area to be exposed. For example, the focus drive of the substrate stage 16 is controlled by taking over the focus correction value applied when exposing the exposure area that was exposed immediately before the exposure area to be exposed. On the other hand, when the control unit 20 calculates an approximate surface 106 whose inclination is outside the range of the threshold value 102, the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the approximate surface 106.

In this embodiment, for an exposure area (first exposure area) in which the inclination of the approximation surface does not exceed the range of the threshold value 102, the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the approximation surface of an exposure area exposed prior to that exposure area. This reduces unnecessary drive control of the substrate stage 16 caused by the measurement accuracy of the third measurement unit 17 during focus drive, thereby suppressing the occurrence of stage control residuals (improving synchronization error of the substrate stage 16).

On the other hand, for an exposure area (second exposure area) where the inclination of the approximation surface does not exceed the range of the threshold value 102, the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the approximation surface of the exposure area. Therefore, when the approximation surface of the exposure area varies significantly, it is possible to control the focus drive of the substrate stage 16 with high precision according to the cross-sectional shape of the surface of the exposure area, thereby suppressing the occurrence of focus residuals.

Note that for the first exposure area (third exposure area), no focus correction value has been obtained prior to that. Therefore, for the first exposure area, regardless of whether the inclination of the approximation surface is within or outside the range of threshold 102, the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the approximation surface of that exposure area.

In this embodiment, the tilt of the approximation surface (rotation in the ωY direction) has been described as an example, but it is also possible to control the focus drive in the same way for the tilt of the approximation surface (rotation in the ωX direction). In addition, a predetermined range may be set for the height position of the approximation surface, and if the height position of the approximation surface exceeds the predetermined range, the focus drive of the substrate stage 16 may be controlled based on a correction value for focus drive obtained from the approximation surface. In addition, if the height position of the approximation surface does not exceed the predetermined range, the focus drive of the substrate stage 16 may be controlled based on, for example, a correction value for focus drive applied when exposing the exposure area that was previously exposed.

In other words, if the information about the approximation surface exceeds a predetermined range, the focus drive of the substrate stage 16 is controlled based on a focus correction value related to focus drive obtained from the approximation surface. Also, if the information about the approximation surface does not exceed the predetermined range, the focus drive is controlled based on, for example, the focus correction value applied when exposing the exposure area that was previously exposed. Here, the information about the approximation surface includes at least one of the inclination of the approximation surface and the height position of the approximation surface.

Second Embodiment
In this embodiment, a technique for reducing a stage control residual (focus residual) in a defective shot region including the outer periphery of the substrate 15 among the shot regions of the substrate 15 will be described. FIG. 7 is a diagram showing measurement points 30c ₁ to 30c ₃ in a defective shot region 15b including the outer periphery of the substrate 15, and measurement results (focus measurement results) z1 to z2 of the surface position at the measurement points 30c ₁ and 30c _2. Referring to FIG. 7, in the defective shot region 15b, since the measurement point 30c ₃ is a measurement point (invalid channel) that is not on the substrate, the third measurement unit 17 cannot measure the surface position for the measurement point 30c _3. As a result, the measurement span of the third measurement unit 17 becomes narrower, and the accuracy of the approximation surface 111 that approximates the cross-sectional shape of the surface of the exposure region including the measurement points 30c ₁ and 30c ₂ decreases.

8A and 8B are diagrams showing the positional relationship of a plurality of measurement points _{30c1 to 30c6 formed by the third measurement unit 17 in each of the missing shot regions 15c and 15d including the outer periphery of the substrate 15. The measurement points 30c1 to 30c6 are} formed side by side in the X direction.

8A, in the missing shot region 15c, the measurement points _30c1 to _30c4 are valid channels, and the measurement points _30c5 and _30c6 are invalid channels. Also, in the missing shot region 15d, the measurement points _30c1 and _30c2 are valid channels, and the measurement points _30c1 to _30c6 are invalid channels. In this way, the measurement span of the third measurement unit 17 changes according to the number of valid channels, and the accuracy of the approximation surface also changes.

In this embodiment, the threshold value set for the approximation surface is optimized for each exposure area, making it possible to control the focus drive of the substrate stage 16 with high precision even in a missing shot area that includes the outer periphery of the substrate 15.

Figure 9 is a diagram showing an example of the threshold value 112 set for the approximation surface 111 of the missing shot area including the outer periphery of the substrate 15. Referring to Figure 9, the measurement accuracy 103 of the third measurement unit 17 is constant, but the measurement span 113 of the third measurement unit 17 is shortened. Therefore, the range of the threshold value 112 set for the approximation surface 111 of the missing shot area, i.e., the range sandwiched between the two lines 112a and 112b, is wider than the range of the threshold value 102 (see Figure 6) set for the approximation surface 105 of a normal shot area.

When the control unit 20 calculates an approximation surface 111 whose inclination is within the range of the threshold value 112, the focus drive of the substrate stage 16 is controlled without applying the focus correction value obtained from the approximation surface 111, as in the first embodiment. On the other hand, when the control unit 20 calculates an approximation surface 114 whose inclination is outside the range of the threshold value 112, the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the approximation surface 114.

10A and 10B are diagrams showing an example of thresholds set for an approximation surface of a missing shot region when the third measurement unit 17 forms a plurality of measurement points 30c ₁ to 30c ₆ in the X direction. Referring to FIG. 10A, a measurement span 118 of the third measurement unit 17 is determined from the measurement points 30c ₁ to 30c ₄ , which are valid channels among the measurement points 30c ₁ to 30c _6. Then, a threshold 119 is set based on the measurement accuracy 103 of the third measurement unit 17 and the measurement span 118 of the third measurement unit 17. Also, referring to FIG. 10B, a measurement span 120 of the third measurement unit 17 is determined from the measurement points 30c ₁ and 30c ₂ , which are valid channels among the measurement points 30c ₁ to 30c _6. Then, a threshold 121 is set based on the measurement accuracy 103 of the third measurement unit 17 and the measurement span 120 of the third measurement unit 17.

According to this embodiment, it is possible to control the focus drive of the substrate stage 16 with high precision even for missing shot areas including the outer periphery of the substrate 15, thereby suppressing the occurrence of stage control residuals.

Third Embodiment
In this embodiment, the control unit 20 predicts the cross-sectional shape of the surface of the exposure area based on the measurement results of the surface position of the shot area of the substrate 15 and the measurement results of the surface position of adjacent shot areas, and obtains a predicted cross-sectional shape w3 for the actual cross-sectional shape w2 of the surface of the exposure area. The predicted cross-sectional shape w3 is obtained by performing a function approximation, for example, a cubic function approximation.

Figure 11 is a diagram showing an example of thresholds set for the actual cross-sectional shape w2 of the surface of the exposure region, the predicted cross-sectional shape w3 of the surface of the exposure region, and the approximation surface of the exposure region. Referring to Figure 11, in this embodiment, the threshold 115 is set based on the measurement accuracy 103 of the third measurement unit 17, the measurement span 104 of the third measurement unit 17, and the predicted cross-sectional shape w3. Specifically, the threshold 115 is set from the measurement accuracy 103 and measurement span 104 of the third measurement unit 17 with the predicted cross-sectional shape w3 as a reference. Therefore, the range of the threshold 115, i.e., the range between the two lines 115a and 115b, shifts relative to the range of the threshold 102 (see Figure 6).

When the control unit 20 calculates an approximation surface 116 whose inclination is within the range of the threshold value 115, the focus correction value obtained from the approximation surface 116 is not applied, and the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the predicted cross-sectional shape w3. On the other hand, when the control unit 20 calculates an approximation surface 117 whose inclination is outside the range of the threshold value 115, the focus drive of the substrate stage 16 is controlled based on the focus correction value obtained from the approximation surface 117.

According to this embodiment, it is possible to control the focus drive of the substrate stage 16 with high precision, thereby suppressing the occurrence of stage control residuals. This embodiment is particularly useful in cases where changes in the cross-sectional shape of the surface of the substrate 15 are overshadowed by fluctuations in the approximation surface caused by the measurement precision of the third measurement unit 17.

Fourth Embodiment
The exposure process (exposure method) in the exposure device 80 will be described with reference to Fig. 12. Fig. 12 is a flow chart for explaining the exposure process in this embodiment.

In S1002, the control unit 20 calculates an approximate surface that approximates the cross-sectional shape of the surface of the exposure area that includes each measurement point based on the focus measurement results at each measurement point on the substrate 15.

In S1004, the control unit 20 determines whether the drive amount of the substrate stage 16 in focus drive exceeds the upper limit based on the focus correction value obtained from the approximation surface calculated in S1002. If the drive amount of the substrate stage 16 in focus drive exceeds the upper limit, the process proceeds to S1006. On the other hand, if the drive amount of the substrate stage 16 in focus drive does not exceed the upper limit, the process proceeds to S1008.

In S1006, the control unit 20 exposes (scans and exposes) the exposure area of the substrate 15 while controlling the focus drive so as to drive the substrate stage 16 at the upper limit drive amount.

In S1008, the control unit 20 determines whether the information about the approximation surface calculated in S1002 exceeds a predetermined range. If the information about the approximation surface calculated in S1002 does not exceed the predetermined range, the process proceeds to S1010. On the other hand, if the information about the approximation surface calculated in S1002 exceeds the predetermined range, the process proceeds to S1012.

In S1010, the control unit 20 exposes (scanning exposes) the exposure area of the substrate 15 while controlling the focus drive of the substrate stage 16 based on the focus correction value obtained from the approximation surface of the exposure area that was exposed before the exposure area to be exposed.

In S1012, the control unit 20 exposes (scans and exposes) the exposure area of the substrate 15 while controlling the focus drive of the substrate stage 16 based on the focus correction value obtained from the approximation surface calculated in S1002.

Figure 13 is a diagram for explaining that the above-mentioned exposure process improves the stage control residual (focus residual). Referring to Figure 13, in an ideal state in which the measurement results at each measurement point 30 do not include measurement errors, the substrate stage 16 is driven along the cross-sectional shape w4 of the surface of the substrate 15 in focus driving, so no stage control residual occurs. However, if the measurement results at each measurement point 30 include measurement errors, in the conventional technology, the substrate stage 16 is driven in focus driving while deviating significantly from the cross-sectional shape w4 of the surface of the substrate 15, so a large stage control deviation 131 occurs. On the other hand, in this embodiment, even if each measurement point 30 includes measurement errors, the substrate stage 16 is driven in focus driving approximately along the cross-sectional shape w4 without deviating significantly from the cross-sectional shape w4 of the surface of the substrate 15. Therefore, in this embodiment, the occurrence of the stage control deviation 132 is suppressed, and the stage control deviation 132 can be suppressed to a relatively small value.

In each of the above-described embodiments, the third measurement unit 17 is used to measure the surface positions in the height direction of the multiple measurement points in the exposure area of the substrate 15 to be exposed in the exposure process sequence, but the present invention is not limited to this. For example, the third measurement unit 17 may be used to measure (pre-measure) the surface positions in the height direction of the multiple measurement points in the exposure area of the substrate 15 to be exposed before the exposure process sequence. Alternatively, an external measurement device may be used to measure (pre-measure) the surface positions in the height direction of the multiple measurement points in the exposure area of the substrate 15 to be exposed, and the surface positions may be obtained from the external measurement device. In this case, the control unit 20 functions as an acquisition unit that acquires the surface positions in the height direction of the multiple measurement points in the exposure area of the substrate 15 to be exposed. In addition, in the pre-measurement, the measurement origin of the substrate stage 16 may be measured multiple times at intervals finer than the measurement intervals of each measurement point 30 on the substrate. This allows the surface position in the height direction to be measured with higher accuracy over the entire surface of the substrate 15.

The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing articles such as liquid crystal display elements, semiconductor elements, flat panel displays, and MEMS. The manufacturing method includes a step of exposing a substrate coated with a photosensitive agent using the above-described exposure apparatus 80 or exposure method, and a step of developing the exposed photosensitive agent. In addition, a circuit pattern is formed on the substrate by performing an etching process, an ion implantation process, etc., using the developed photosensitive agent pattern as a mask. These steps of exposure, development, etching, etc. are repeated to form a circuit pattern consisting of multiple layers on the substrate. In a post-process, dicing (processing) is performed on the substrate on which the circuit pattern is formed, and chip mounting, bonding, and inspection processes are performed. The manufacturing method may also include other well-known processes (oxidation, film formation, deposition, doping, planarization, resist stripping, etc.). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to the conventional method.

The present invention does not limit the lithography apparatus to an exposure apparatus, but can also be applied to, for example, an imprint apparatus. The imprint apparatus brings an imprint material placed (supplied) on a substrate into contact with a mold (original plate) and applies energy for hardening to the imprint material, thereby forming a pattern of a hardened material to which the pattern of the mold has been transferred. The present invention can also be applied to external inspection devices for substrates.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to disclose the scope of the invention.

12: Original 13: Original stage 14: Projection optical system 15: Substrate 16: Substrate stage 17: Third measurement unit 20: Control unit 80: Exposure device

Claims (14)

An exposure apparatus that exposes a substrate through an original, comprising:
a substrate stage for holding the substrate;
an acquisition unit that acquires, for each of a plurality of exposure regions to be exposed on the substrate, surface positions in a height direction of a plurality of measurement points of the exposure region;
a control unit that controls driving of the substrate stage in the height direction when exposing each of the plurality of exposure regions based on the surface position acquired by the acquisition unit; and
having
The control unit is
determining an approximation surface that approximately represents a cross-sectional shape of a surface of the exposure area from the surface position acquired by the acquisition unit for each of the plurality of exposure areas;
An exposure apparatus characterized in that, for a first exposure area among the multiple exposure areas, in which information regarding the approximate surface does not exceed a predetermined range, the driving is controlled based on a correction value for the driving obtained from an approximate surface that approximately represents the cross-sectional shape of the surface of an exposure area exposed before the first exposure area. The exposure apparatus according to claim 1, characterized in that, for a second exposure area among the multiple exposure areas in which information about the approximation surface exceeds a predetermined range, the control unit controls the drive based on a correction value for the drive obtained from an approximation surface that approximately represents the cross-sectional shape of the surface of the second exposure area. The exposure apparatus according to claim 1 or 2, characterized in that the control unit controls the drive of a third exposure area, which is exposed first among the multiple exposure areas, based on a correction value for the drive obtained from an approximation surface that approximately represents the cross-sectional shape of the surface of the third exposure area. The exposure device according to any one of claims 1 to 3, characterized in that the control unit controls the driving of the first exposure area based on a correction value for the driving used when exposing an exposure area that was exposed immediately before the first exposure area. The exposure apparatus according to any one of claims 1 to 4, characterized in that the acquisition unit includes a measurement unit that measures the surface position. The exposure apparatus according to claim 5, characterized in that the predetermined range is set based on the measurement accuracy of the measurement unit for the multiple measurement points and the measurement range of the measurement unit for the multiple measurement points. The exposure apparatus according to any one of claims 1 to 4, characterized in that the acquisition unit acquires the surface position measured by an external measurement device. The exposure apparatus according to claim 7, characterized in that the predetermined range is set based on the measurement accuracy of the external measurement device for the multiple measurement points and the measurement range of the external measurement device for the multiple measurement points. The exposure apparatus according to claim 6 or 8, characterized in that the measurement range is determined based on measurement points among the plurality of measurement points at which the surface position can be measured. The exposure apparatus according to claim 6 or 8, characterized in that the predetermined range is set for each of the multiple exposure regions based on the predicted cross-sectional shape of the surface of the exposure region. The exposure apparatus according to claim 10, characterized in that the approximate surface that approximates the cross-sectional shape of the surface of the exposure area exposed before the first exposure area includes the predicted cross-sectional shape of the surface. The exposure apparatus according to any one of claims 1 to 11, characterized in that the information about the approximation surface includes at least one of the inclination of the approximation surface and the height direction position of the approximation surface. An exposure method for exposing a substrate through a mask, comprising the steps of:
acquiring surface positions in a height direction of a plurality of measurement points of each of a plurality of exposure areas to be exposed on the substrate;
controlling, based on the acquired surface position, driving of a substrate stage that holds the substrate in the height direction when exposing each of the plurality of exposure regions;
having
In the step of controlling the driving of the substrate stage,
determining an approximation surface that approximately represents a cross-sectional shape of a surface of the exposure area from the acquired surface position for each of the plurality of exposure areas;
An exposure method characterized in that, for a first exposure area among the multiple exposure areas, in which information regarding the approximation surface does not exceed a predetermined range, the driving is controlled based on a correction value for the driving obtained from an approximation surface that approximately represents the cross-sectional shape of the surface of an exposure area exposed before the first exposure area. exposing a substrate using the exposure method according to claim 13;
developing the exposed substrate;
producing an article from the developed substrate;
A method for producing an article, comprising the steps of:

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